EP-A 440 957 discloses dispersions of polythiophenes, constructed from structural units of formula (I):
in which R1 and R2 independently of one another represent hydrogen or a C1-C4 alkyl group or together form an optionally substituted C1-C4-alkylene residue, in the presence of polyanions.
EP-A-686 662 discloses mixtures of A) neutral polythiophenes with the repeating structural unit of formula (I),
in which R1 and R2 independently of one another represent hydrogen or a C1-C4 alkyl group or together represent an optionally substituted C1-C4 alkylene residue, preferably an optionally with alkyl group substituted methylene, an optionally with C1-C12-alkyl or phenyl group substituted 1,2-ethylene residue or a 1,2-cyclohexene residue, and B) a di- or polyhydroxy- and/or carboxy groups or amide or lactam group containing organic compound; and conductive coatings therefrom which are tempered to increase their resistance preferably to <300 ohm/square. Furthermore, the potential use of such layers as electrodes in electroluminescence devices is disclosed.
ORGACON™ EL film is a commercially available subbed polyethylene terephthalate support coated on one side with a transparent layer of electrically conducting poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) [PEDOT/PSS] produced by Agfa-Gevaert N.V. It is promoted in the current brochure for this product as a low cost alternative to polyethylene terephthalate film coated with a transparent coating of indium tin oxide (ITO) for use in electroluminescent lamps. T. Cloots et al. in the extended abstracts of the 5th International Conference on the Science and Technology of Display Phosphors held at San Diego on Nov. 8-10, 1999 disclosed a comparison of electroluminescent lamps in which ITO-PET supports have been replaced with ORGACON™ EL film. However, under simulated ageing conditions of 60° C. and 90% relative humidity electroluminescent devices produced with ORGACON™ EL film (see COMPARATIVE EXAMPLES 3 and 4) exhibited markedly inferior lifetime compared with electroluminescent devices produced with ITO-PET (see COMPARATIVE EXAMPLES 1 and 2).